1. Field of the Invention
The present invention relates to a charging control method and system for an electric vehicle, which sets different charging control methods based on the state of charge (SOC) of the auxiliary battery of the electric vehicle, thus improving the charging efficiency of the electric vehicle.
2. Description of the Related Art
Recently, due to the insufficiency of environment-friendly products and energy attributable to environmental pollution, the conservation of energy resources has been emphasized. Accordingly, even in the automobile industry, electric vehicles, which are environment-friendly and have high energy efficiency, have been developed to improve competitiveness. Recently, owing to the improvement in the performance of batteries or the like and the reduction in the cost of batteries, the use of electric vehicles as general-purpose vehicles has been realized. Electric vehicles are characterized in that carbon dioxide is not emitted during driving and excellent environmental performance is exhibited, and in which the attraction of vehicles, such as improved acceleration responsiveness or a sensation of silent and smooth driving, has been improved.
Typically, an electric vehicle requires operating power for electronic units mounted therein and driving power for driving the motor that moves the electric vehicle. The operating power and the driving power are supplied from a battery. Generally, a main battery in which multiple battery cells are connected in series is used to provide the driving power. However, since the electronic units of an electric vehicle are operated at a voltage lower than that of the operating power and the driving power, they are configured to be driven by receiving power obtained by down-converting power supplied from the main battery, or by receiving power from an additional auxiliary battery that supplies power suitable for electronic units. Particularly, the electronic units also include an electronic unit for starting the electric vehicle.
Therefore, for electric vehicles, technology for preventing the discharge of an auxiliary battery has been continuously developed to prevent the occurrence of the situation in which starting or the use of electronic units becomes impossible. The related art teaches a control method that enables an auxiliary battery to be charged as required even when an electric vehicle is in an ignition (IG)-ON state, thus improving the reliability and marketability of electric vehicles.
However, such conventional technology merely provides a control method for charging when the voltage of an auxiliary battery is low, and does not provide a control method in relation to the charging control strategy for the auxiliary battery when the voltage of the auxiliary battery is sufficiently high or is maintained at a suitable voltage level. Accordingly, the auxiliary battery may continue to be charged even when the voltage of the auxiliary battery is sufficiently high, and thus the fuel efficiency of the electric vehicle may deteriorate.
The foregoing is intended merely to aid in the better understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.